Counterbalance



Oct. 23, 1928.

1,688,361 H. H. TALBOT COUNTERBALANCE Filed Aug. 16, 1923 2 Sheets-Sheetl F .l

INVENTOR H. H. TALBOT COUNTERBALANCE Oct. 23, 1928. 4 1,688,361

Filed Aug. 16, 1923' Sheets-Sheet 2 gm k INVENTOR Patented Oct. 23,1928.

Units!) STATES PATENTOFFICE.

HOWARD H. TALBOT, or PITTSBURGH, PENNSYLVANIA, assreNon To'nNI'rEnnNGr-I NEERING & FOUNDRY COMPANY, or rrrrssunon, rrNNsYr,Vania, A conronA-IION on PENNSYLVANIA.

CQUNTERBALANCE.

Application flledlAugnst 16,1923. Serial na'esnesv.

This invention relates to counterbalances, and is particularly usefulfor counterbalancing the moving 'head of a-metal working machine, as ashear, a punch, or the like.

In apparatus of'this character, it is desirable to apply a substantiallyconstant counter-force to the moving part, as is well known, and thishas ordinarily been done by a counter-weight in one form or another. Iutilize means exerting avarying counter-force, as

for example, afspring, and utilize suclivarying counter-force-in aninversely varying amount. This may be done by providing an arm throughwhich the counter-force is exerted and so designing'the arm that theefi'ective length varies with the iriovementof the apparatus whichis'tobe balanced. I am thus enabled to utilize a relatively small springas contrasted with the ordinary sy temof counterweights and levers andthe entire counterbalance may be confined to a very small space whileachieving the desired results in a perfectly satisfactory manner. Ahelica spring its-preferably employed- I further provide for connectingan arm to each end of the helical. springand connecting each of thesearms to the apparatus to be counterbalanced, both arms being ,movedsimultaneously. In this manner, I

am enabled to materially reduce the space occupied by the counterbalancesince each of the arms need only to be moved one-half the distance whichwould be necessary 7 if one arm alone were employed. This con structionalso materially simplifies the design. 1

In the accompanying drawings illustrating the present preferredembodiment of my invention:

Figures 1 and 2 are diagrammatic views illustrative of my invention;

Figure 3 is a top plan view of a counterbalance embodying the invention;and

Figure & is a central vertical section, partly in elevation, of theapparatus shown in Figure 3.

Referring to the diagrams of Figures 1 and 2, there is illustrated apair of hell crank levers L and L pivoted at points ;0 and 1)respectively. The lower arms Z and Z of the bell cranks carry the weightW which is to be counterbalanced. The upper arms Z and Z carry acompression spring S and are urged apart thereby. It will be seen thatthe effecinclined levers 9 keyed thereto.

tive length of the upper lever arms Z and Z is the perpendiculardistancer from the pivot points" to the axis of the spring S, while theeffective length of the lower lever arms Z and Z= is expressed by thedistance R.

Since the apparatus is symmetrical, one side alone may be considered,and for this size the length of the. spring S when free and unloaded maybe expressed as S and the original compression as C. If the weight W isproperly counterbalanced, or rather one half W,since only one side ofthe counterbalanceis being considered, the equation is 1/2WR=7cC'/-,where his the scaleof the spring. i I 1 Referring to Figure 2,which'shows the load WV in lowest position, it will be seen that thecompression of thespring is now C and its effective arm is reduced to a"while the load, one-half W, is still acting at the distance R. Since thespring load has increased during-the downward movement, a greaterspreading force is exerted between the arms Z and Z but the mechanicalad'- vantage of the lever considered as a whole has changed, with theresult that the counterforce available to return the moving parts tooriginal position remains substantially constant.

Referring to the embodiment of the invention illustrated in Figures 3and 4, there is shown a base plate '2 carried by guides 3 of a metalworking machine having a vertically reciprocable head 1. Rods 5 connectthe head 4 to oppositely disposed levers 6 keyed to a pair of parallelshafts 7. The shafts 7 ar'ecarried in bearing brackets 8 secured to theplate 2 and each has a pair of The lovers 9 are connected to a pair ofspring plates 10 by take-up links 11 provided with nuts 12-for varyingthe original distance between the spring plates 10. A rod 13 runsthrough the spring plates 10 and carries a central spring plate 14, oneither side; of which are placed helical compressionsprings 15. A cover16 may be placed over the entire counterbalance.

As the head 4: moves downwardly, the springs 15 are compressed andexerta varying counter-force, but the effective length of the arms 9 changeson account of the varying inclinationthereof and a substantially constant counter-moment is available for returning the head 1 to itsoriginal position after many advantages of the invention.

I provide a counterbalance utilizing means exerting .a varyingcounter-force by providlng means for utilizing the counteriorce in aninversely varying amount. The entire apparatusis simple and rugged, isfar; more nated. I

It will be understood that the apparatus ,sightly than theusualcounterweights employed, and'is highly advantageous ncomparisontherewith since. it is self-contained and therefore:absolutelvi safe while the heavy apparatus present" in the ordinaryform of counterweight 1s done away w th and numerous inertia forcesthereby elimineed not be designed to exert a substantially constantcounter-force,as certain variations in theeounter-i orce may bedesirable in certaintypesof apparatus and this maybereadily provided..Itwill be further understood that the var ation 1n;the proportion ofthe spring force utilized may lie-secured other.

means than that illustrated, as, for example, by translation cams; for,while I have shown the preferred formof my ,mventiomit is not limitedthereto, but may be otherwise em bodied within the scope ofthe followingclaims.

Iclaim: J

1. 'A counterbalance includinganarin and a connectionthereon to'theobject't-obe countel-balanced, whereby'a' load moment is set up, an armand a spring connected thereto, the arms being adapted to varyineffective lengtlnwherebythe counter-moment is maintainedsubstantiallyequal to the load moment.

'2. 'A coun'terbalance including an arm and a connection thereon to theobject to be connterbalanced, wherebya load moment is .set

up, anarm and a spring under initial load connected thereto, the armsbeing adapted to vary in eflective lengtl'1,wl1ereby the counter-momentis maintained substantially equal to the load moment. I I

3. A counterbalance including an arm and a connection thereon to theobect to be counterbalanced, whereby a load momentis set up, an arm and aspring under initial load connected thereto, the armsbeing adapted tovary in effective length, whereby the couritermoment ismaintainedsubstantially equal to the load moment, and meansfor adjustingthe initial load.

4. A counterbalance" including a pair of arms and connections thereontothe object 1 to be counterbalanced, whereby load moments are set up, apair of arms connectedone to each of the first pair and connected bymeans tending to supply a Varying counter-"force asthe' arms aremoved,'thearms being adapt- I ed to vary' in effective length, wherebythe counter-moment is maintained substantially equal to the load'moment.I

5. A counterbalance for the moving head ofa metal working machine,comprising a head to be counterbalanced, a counterbalancmg. spring, anda bell crank connectingthe spring a-ndthehead, one-arin of said bellcrank being adapted to maintain a substantially constant length and theother arm being adapted to provide an effective length which variesinversely with the power of the spring. I

In testimony whereof I my hand.

'HQWARD H. TALBOT.

have hereunto set

